Short luteal phase????

I ovulated Monday and started bleeding Friday and bleeding enough again today to fill light tampons. So I suspect this is my period starting, even though I have no cramping like I usually do. Just bad backaches. Spotting mid cycle has not occurred once in the last year that I’ve been off birth control.

There were two other cycles in the last 6 months we’ve been trying that had shorter than normal luteal phases. Other than that I have been spot on 14 days.

Question is if this is cause for concern? Is it normal to occasionally have a short luteal phase or could it be luteal phase defect?